“the Senate has always been unequal, long giving less populous states an outsized voice relative to their population.1 But for more than a century, this hasn’t posed much of an issue: Until the 1960s, Republicans and Democrats competed for both densely and sparsely populated states at roughly the same rate
But over the last several decades, that’s changed. The parties have reorganized themselves along urban-rural lines, and there is now a clear and pronounced partisan small-state bias in the Senate thanks to mostly rural, less populated states voting increasingly Republican. In fact, it’s reached the point that Republicans can win a majority of Senate seats while only representing a minority of Americans.”
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“Much of this follows from the post-civil rights realignment of American partisan politics, in which the Democratic Party became more consistently liberal (and thus more appealing in big, largely urban states), and the Republican Party became more consistently conservative (and thus more appealing in small, largely rural states). But that gap has also widened in recent years, especially starting in 2015, when Republicans took back a Senate majority, flipping seats in small states like West Virginia, South Dakota, Arkansas, Alaska and Montana — all states that will be tough for Democrats to regain in 2020.”